tetrapeptide comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2026-02-16. Where a claim depends on a specific study, the study is described rather than over-claimed.
Several names circulate for the same molecule, including epitalon, epithalone, epithalamin tetrapeptide, and the sequence code AEDG. A CAS registry number, 307297-39-8, is commonly cited for it, though catalogue entries should be checked against supplier documentation because mislabelled records occur. In its usual form the peptide carries free amino and carboxyl termini and is neither glycosylated nor lipidated. Researchers distinguish the defined tetrapeptide from epithalamin itself, a crude pineal preparation containing many peptides that is not chemically characterised.
Material supplied for laboratory use is normally a lyophilised white to off-white powder that dissolves readily in water and in isotonic saline. Lyophilised cakes are hygroscopic and should be equilibrated to room temperature before opening to limit condensation on the solid. Solutions are typically prepared at milligram-per-millilitre concentrations and divided into single-use aliquots, because repeated freeze–thaw cycles degrade short peptides. Aqueous solutions are far less stable than the dry powder, and identity is usually verified by mass spectrometry alongside purity estimation from reversed-phase high-performance liquid chromatography.
Published studies on epitalon are dominated by a small number of research groups, and independent replication in other laboratories remains limited. Proposed mechanisms include activation of telomerase and modulation of melatonin rhythms, but the evidence for either rests mainly on cell cultures and animal models. Whether the peptide produces comparable effects in humans is an open question, and the absence of large controlled trials means the literature is best read as exploratory rather than settled.
Epitalon is a synthetic four-amino-acid peptide with the sequence alanine-glutamate-aspartate-glycine, commonly abbreviated AEDG. Its molecular formula is C14H22N4O9, and its calculated molar mass is approximately 390.35 grams per mole. The compound is a short fragment related to a peptide fraction isolated from bovine pineal gland extracts, and it is normally supplied as a lyophilised powder intended for laboratory research. It is not a registered pharmaceutical product in most countries.
| Property | Value | Notes |
|---|---|---|
| Amino acid sequence | Ala-Glu-Asp-Gly | Linear tetrapeptide, also written AEDG |
| Molecular mass | About 390.35 g/mol | Value calculated from the sequence |
| Appearance | White to off-white powder | Lyophilised material forms a loose cake |
| Solubility | Freely soluble in water | Also dissolves in isotonic saline |
| Storage | -20 °C, desiccated | Aliquot solutions to avoid freeze–thaw cycling |
The parent extract epithalamin was characterised as a low-molecular-weight fraction of pineal tissue rather than a single defined chemical entity. Researchers fractionated it and tested successive fragments for activity, a screening approach typical of peptide discovery work in that era. Epitalon emerged from that process as one of the shorter sequences of interest. Because the original extract was never fully resolved into individual components, claims about which constituent drives a given effect rest on inference. This distinction matters when reading older reports that attribute extract observations to the tetrapeptide itself.
Epitalon is a synthetic tetrapeptide with the residue sequence alanine-glutamate-aspartate-glycine, commonly abbreviated AEDG. Its monoisotopic mass is approximately 390.35 daltons, and it is usually supplied as a lyophilised trifluoroacetate or acetate salt. The compound was derived from a pineal gland extract called epithalamin, a heterogeneous preparation investigated in the former Soviet Union. Researchers associated with the Saint Petersburg Institute of Bioregulation and Gerontology described the tetrapeptide as a constituent fragment of that extract. Commercial material is offered as a laboratory reagent rather than as a finished pharmaceutical product.
== Professional activities == Dr. Goldstein was the co-founder and first president and scientific director of the Institute for Advanced Studies in Aging and Geriatric Medicine, a nonprofit research institute that supports research and educational activities. He also served as a member of the board of trustees of the Albert Sabin Vaccine Institute and of the board of directors of the Richard B. and Lynn V. Cheney Cardiovascular Institute. Currently, he serves as the chairman of the board and chief scientific advisor for RegeneRx Biopharmaceuticals, a public company developing novel wound-healing and remodeling therapeutics.
=== B cells === TGF-β1 has similar effects on B cells that also vary according to the differentiation state of the cell. It inhibits proliferation, stimulates apoptosis of B cells, and controls the expression of antibody, transferrin and MHC class II proteins on immature and mature B cells.
Immunodeficiency, also known as immunocompromise, is a state in which the immune system's ability to fight infectious diseases and cancer is compromised or entirely absent. Most cases are acquired ("secondary") due to extrinsic factors that affect the patient's immune system. Examples of these extrinsic factors include HIV infection and environmental factors, such as nutrition. Immunocompromisation may also be due to genetic diseases/flaws such as SCID. In clinical settings, immunosuppression by some drugs, such as steroids, can either be an adverse effect or the intended purpose of the treatment. Examples of such use include organ transplant surgery as an anti-rejection measure and in patients with an overactive immune system, such as in autoimmune diseases. Some people are born with intrinsic defects in their immune system, or primary immunodeficiency. A person who has an immunodeficiency of any kind is said to be immunocompromised. An immunocompromised individual may be particularly vulnerable to opportunistic infections, in addition to normal infections that could affect anyone. It also decreases cancer immunosurveillance, in which the immune system scans the body's cells and kills neoplastic ones. They are also more susceptible to infectious diseases owing to the reduced protection afforded by vaccines.
Berlin and Ripon joined the South Central Conference, Waupun became members of the Capitol Conference, Winneconne was accepted into the Bay Conference and the remaining three schools (Kettle Moraine Lutheran, Kewaskum and Plymouth) combined with four other schools (Port Washington, Sheboygan South, West Bend East and West Bend West) to form the Glacier Trails Conference.
=== Direct printing === Two different methods for the direct application of indigo were developed in England in the 18th century and remained in use well into the 19th century. The first method, known as "pencil blue" because it was most often applied by pencil or brush, could be used to achieve dark hues. Arsenic trisulfide and a thickener were added to the indigo vat. The arsenic compound delayed the oxidation of the indigo long enough to paint the dye onto fabrics.
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== Bibliography == Boyd Orr, John (1905). Scotch Church Crisis: The Full Story of the Modern Phase of the Presbyterian Struggle. Glasgow: John M'Neilage. —————— (1929). Minerals in Pastures and Their Relation to Animal Nutrition. London: Lewis. —————— (1934). The National Food Supply and Its Influence on Public Health. London: King. —————— (1936). Food, Health and Income. London: Macmillan. —————— (1937). Nutritional Science and State Planning.in (Orr) —————— (1940). Nutrition in war. Fabian Tract 251. London: Fabian Society. —————— (1942). Fighting for What?. London: Macmillan. —————— (1943). Food and the People. London: Pilot Press. —————— (1945). Welfare and Peace. London: National Peace Council. —————— (1946). A Charter for Health. London: Allen & Unwin. —————— (1948). Food: The Foundation of World Unity. London: National Peace Council. —————— (1950). International Liaison Committee of Organisations for Peace: A New Strategy of Peace. London: National Peace Council. —————— (1957). Feast and famine: The wonderful world of food. London: Rathbone Books. —————— (1958). The Wonderful World of Food: The Substance of Life. Garden City, NY: Garden City Books. —————— (1966). As I recall: the 1880s to the 1960s. with an introduction by Ritchie Calder. London: MacGibbon & Kee. with other authors Boyd Orr, John; Lubbock, David (1940). Feeding the people in war time. London: Macmillan – via Internet Archive. Boyd Orr, John; Lubbock, David (1964) [First published 1953]. The White Man's Dilemma: Food and the Future (2nd ed.). London: Allen & Unwin. Boyd Orr, John (1968).
Gate of Flesh (Japanese: 肉體の門, Hepburn: Nikutai no mon) is a 1964 Japanese film based on a novel by Taijiro Tamura and directed by Seijun Suzuki. The first of Suzuki's "flesh trilogy" (followed by Story of a Prostitute and Carmen from Kawachi), the series is considered the "crowning achievement" of his period working at the production house Nikkatsu. The film is viewed as a direct and allegorical critique of Japan's Occupation and subsequent development, which rather than breaking with the country's pre-war militaristic, authoritarian social structures only sees their reconstitution in the post-war period.
CH3CH2Br + SC(NH2)2 → [CH3CH2SC(NH2)2]Br [CH3CH2SC(NH2)2]Br + NaOH → CH3CH2SH + OC(NH2)2 + NaBr The thiourea route works well with primary halides, especially activated ones. Secondary and tertiary thiols are less easily prepared. Secondary thiols can be prepared from the ketone via the corresponding dithioketals. A related two-step process involves alkylation of thiosulfate to give the thiosulfonate ("Bunte salt"), followed by hydrolysis. The method is illustrated by one synthesis of thioglycolic acid:
Although there are differences between eukaryotic and prokaryotic DNA synthesis, the following section denotes key characteristics of DNA replication shared by both organisms. DNA is composed of nucleotides that are joined by phosphodiester bonds. DNA synthesis, which takes place in the nucleus, is a semiconservative process, which means that the resulting DNA molecule contains an original strand from the parent structure and a new strand. DNA synthesis is catalyzed by a family of DNA polymerases that require four deoxynucleoside triphosphates, a template strand, and a primer with a free 3'OH in which to incorporate nucleotides. In order for DNA replication to occur, a replication fork is created by enzymes called helicases which unwind the DNA helix. Topoisomerases at the replication fork remove supercoils caused by DNA unwinding, and single-stranded DNA binding proteins maintain the two single-stranded DNA templates stabilized prior to replication. DNA synthesis is initiated by the RNA polymerase primase, which makes an RNA primer with a free 3'OH. This primer is attached to the single-stranded DNA template, and DNA polymerase elongates the chain by incorporating nucleotides; DNA polymerase also proofreads the newly synthesized DNA strand. During the polymerization reaction catalyzed by DNA polymerase, a nucleophilic attack occurs by the 3'OH of the growing chain on the innermost phosphorus atom of a deoxynucleoside triphosphate; this yields the formation of a phosphodiester bridge that attaches a new nucleotide and releases pyrophosphate.
Sources: en.wikipedia.org
== Mechanism of action == The mechanism of action of methyldopa is not fully clear. It may reduce the dopaminergic and serotonergic transmission in the central and peripheral nervous system and it indirectly affects norepinephrine (noradrenaline) synthesis by way of inhibiting dopamine synthesis. Methyldopa acts on alpha-2 adrenergic receptors, which are found on the pre synaptic nerve terminal. This inhibits the release of norepinephrine from the presynaptic neuron. The S-enantiomer of methyldopa is a competitive inhibitor of the enzyme aromatic L-amino acid decarboxylase (LAAD), which converts L-DOPA into dopamine. L-DOPA can cross the blood–brain barrier and thus methyldopa may have similar effects. LAAD converts it into alpha-methyldopamine, a false precursor to norepinephrine, which in turn reduces synthesis of norepinephrine in the vesicles. Dopamine beta hydroxylase (DBH) converts alpha-methyldopamine into alpha-methylnorepinephrine, which is an agonist of the presynaptic α2-adrenergic receptor causing inhibition of neurotransmitter release. Methyldopa has been found to be a monoamine depleting agent.
== Yeast == The selection of yeast used for cider production is critical to the quality of the final product. As with other fermented beverages, like wine and beer, the strain of yeast used to carry out the alcoholic fermentation also converts precursor molecules into the odorants found in the final product. In general, two broad categories of yeast are used for cider making: commercially developed strains and wild, or autochthonous, strains. In either case, the species tend to be either Saccharomyces cerevisiae or Saccharomyces bayanus. Commercial strains are available for purchase from numerous distributors, and their characteristics are typically outlined in manuals from the companies. Selection for fermentation may be based on a yeast's ability to ferment at particular sugar concentrations, temperatures, or pH. Some producers may also select for yeasts that produce killer factors, allowing them to out-compete other yeast in the juice, or they may select yeast that contribute mouthfeel or specific aromas to the cider. "Wild fermentations" occur when autochthonous yeast are allowed to carry out fermentation; indigenous yeasts can spontaneously initiate fermentation without any addition of other yeast strains by the cider maker. Autochthonous yeasts are wild yeast strains that are endemic to the specific location in which a cider is produced; this is the traditional method used for cider making, and many producers feel that the strains unique to their cidery contribute a sense of terroir to their product.
== Clinical significance == There are at least 25 enzymes and specific transport proteins in the β-oxidation pathway. Of these, 18 have been associated with human disease as inborn errors of metabolism. In addition to genetic fatty-acid metabolism disorders, studies indicate that lipid disorders are involved in diverse aspects of tumorigenesis, and fatty acid metabolism makes malignant cells more resistant to a hypoxic environment. Accordingly, cancer cells can display irregular lipid metabolism with regard to both fatty acid synthesis and mitochondrial fatty acid oxidation (FAO) that are involved in diverse aspects of tumorigenesis and cell growth. Several specific β-oxidation disorders have been identified.
Sources: en.wikipedia.org
It is a synthetic tetrapeptide. Its sequence was derived from research on peptide fractions of bovine pineal extract, and the intact AEDG sequence has not been demonstrated as an abundant free peptide in human tissue.
AEDG is the one-letter code for the four amino acids alanine, glutamate, aspartate and glycine in that order. The same molecule is written in three-letter form as Ala-Glu-Asp-Gly.
Identity is normally confirmed by mass spectrometry against the calculated mass of roughly 390.35 g/mol. Purity is then estimated by reversed-phase high-performance liquid chromatography with ultraviolet detection.
It is a synthetic tetrapeptide built from alanine, glutamate, aspartate and glycine. The four residues are joined by standard peptide bonds, giving a linear chain rather than a branched structure.